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GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Sep. 30, 2024
Finite-lived intangible assets:
Cost	$ 204,820		$ 204,820
Accumulated Amortization	(48,507)		(48,507)
Carrying Value	156,313		156,313
Total identifiable intangible assets
Cost	204,838		204,838
Accumulated Amortization	(48,507)		(48,507)
Carrying Value	156,331		156,331		$ 162,816
Amortization expense of intangible assets	3,242	$ 3,113	6,485	$ 6,259
Trademarks
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets:	18		18
Customer relationships
Finite-lived intangible assets:
Cost	199,720		199,720
Accumulated Amortization	(44,789)		(44,789)
Carrying Value	154,931		154,931
Total identifiable intangible assets
Accumulated Amortization	$ (44,789)		$ (44,789)
Customer relationships \| Minimum
Finite-lived intangible assets:
Amortization life	9 years		9 years
Customer relationships \| Maximum
Finite-lived intangible assets:
Amortization life	25 years		25 years
Trade names
Finite-lived intangible assets:
Cost	$ 4,741		$ 4,741
Accumulated Amortization	(3,480)		(3,480)
Carrying Value	1,261		1,261
Total identifiable intangible assets
Accumulated Amortization	$ (3,480)		$ (3,480)
Trade names \| Minimum
Finite-lived intangible assets:
Amortization life	2 years		2 years
Trade names \| Maximum
Finite-lived intangible assets:
Amortization life	5 years		5 years
Non-Compete Agreements And Other Intangible Assets
Finite-lived intangible assets:
Cost	$ 359		$ 359
Accumulated Amortization	(238)		(238)
Carrying Value	121		121
Total identifiable intangible assets
Accumulated Amortization	$ (238)		$ (238)
Non-Compete Agreements And Other Intangible Assets \| Minimum
Finite-lived intangible assets:
Amortization life	3 years		3 years
Non-Compete Agreements And Other Intangible Assets \| Maximum
Finite-lived intangible assets:
Amortization life	8 years		8 years